Hydraulic brake



Dec. 22, 1936. c BOWEN 2,065,044

HYDRAULI G BRAKE Filed Oct. 51, 1954 za 6 I04 7 Z Z INVENTIOR. #555567" C. flows/v A TTORNEYS.

Patented Dec. 22, 1936 UNITED STATES HYDRAULIC BRAKE Herbert 0. Bowen, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich a corporation of California Application October 31, 1934, Serial No. 750,789

Claims.

This invention relates to brakes for motor vehicles, and more particularly to hydraulically actuated brakes for motor vehicles.

Broadly the invention comprehends a hydraulic 5 brake system wherein separate compression devices connected by separate conduits to separate pairs of braking structures are interconnected by an equalizer which also functions as a safety device in the event of leakage in or breakage of either conduit.

In a preferred embodiment of the invention two separate hydraulic brake systems, one for applying the brakes associated with the front 5 wheels of a vehicle and the other for applying the brakes associated with the rear wheels of the vehicle, are arranged for concomitant operation by a single foot pedal lever and are interconnected by mechanism constructed and arranged to function as an equalizer up to a predetermined pressure in the system and thereafter to segregate the systems and function as a safety device in the event of leakage or breakage in either of the systems. I

An object of the invention is to provide a hydraulic brake system including two separate systems interconnected by mechanism operable to equalize the systems up to a predetermined pressure, and thereafter to segregate the systems and function as a safety device inthe event of leakage in or breakage of either of the separate systems.

Other objects of the invention will appear from the following'description taken in connection with the drawing which forms a part of this specification, and in which;-

Figure 1 is a diagrammatical illustration of a hydraulic brake system embodying the invention, and

Figure 2 is an enlarged sectional view of the equalizer mechanism.

Referring to the drawing, I0 and I2 represent corresponding cylinders arranged in parallel relation to one another. In practice, these cylinders are suitably connected to a source of fluid supply substantially as disclosed in my copending application Serial No. 586,474, filed- January 9, 1932.

The cylinder has a discharge port I4 controlled by a valve I6 and connected by a conduit l8 and branched conduits and 22 to'fluid pressure motors 24 and 26 arranged for the actuation of a pair of brakes for a motor vehicle; and the cylinder I2 has a discharge port 28 controlled by a valve 30 connected by a conduit 32 and branched conduits 34 and 36 to fluid pressure motors 38 and 40 arranged for the actuation of another pair of brakes for the motor vehicle.

As shown, each brake includes a fixed support or backing plate 42 on which one of the fluid pressure motors is mounted, a rotatable drum 44 5 associated with the backing plate, and corresponding friction elements 46 pivoted to the backing plate and adapted to be moved by the motor into engagement with the drum against the resistance of a retractile spring 48 connected 10 between the friction elements.

Reciprocable pistons 50 and 52 in the respective cylinders I0 and I2 have on their respective heads corresponding leak-proof cups 54 and 56,

' and springs 58 and 60 interposed between the re- 15 pression strokes by corresponding thrust rods 62 and 64 suitably connected to a rock shaft 66 having keyed or otherwise secured thereto the foot pedal lever 68.

Arranged transversely to the cylinders I0 and 25 I2 is a cylinder 10. This cylinder has 2. diaphragm l2 dividing the cylinder into two corresponding double diametral chambers 14 and I6, and the diaphragm has an orifice 18 providing a communication between the chambers. The 30 chambers I4 and I6 are vented to the atmosphere as at B0 and 82, and threaded in the open end of the chambers are heads 84 and 86.

The head 84 has a concentric extension 88 terminating in a conical end 90. This extension 5 protrudes into the chamber I4 and is provided with a diametral passage 92 communicating with an axial passage 94 in the head, and a fitting 96 threaded in the passage 94 is connected in the conduit I8. Similarly the head 86 has a concen- 0 tric extension 98 terminating in a conical end I00. This extension protrudes into the chamber I6 and is provided with a diametral passage I02 communicating with an axial passage I04 in the head, and a fitting I06 threaded in the passage 45 I04 is connected in the conduit 28.

Pistons I08 and I I0 are mounted for reciprocation in the chambers 14 and I6. The piston I08 has oppositely disposed heads I I2 and H4 of different diameters corresponding to the diflerent 50 diameters of the chamber I4. The head H2 has a concentric extension H6, and the head II4 has aconcentric extension I I8 terminating in a conical end I20 adapted to seat in the orifice I8 and .to close communication between the cham- 55 end-of this passage is adapted to receive the conical end 98 of the extension 88 on the head 8% to close the .passage I28. A leak-proof cup I26 sleeved on the extension I I6 is seated on the head H2, and another leak-proof cup I28 sleeved on .the extension H8 is seated on the head IIl.

These cups prevent the passage of'fluid to the rear of the respective piston heads, and a relatively heavy spring I38 is interposed between the diaphragm I2 and the cup I28 on the head II 8. .This spring urges the piston I88 to its seat on the conical end 98 of the extension 88 on the head 88, in which position the passage I28 is closed.

Similarly, the piston II8 has oppositely disposed heads I32 and I38 of diflerent diameters corresponding to the different diameters of the chamber I6; The head I32 has a concentric extension I36, and the head I38 has a concentric extension I38 terminating in a conical end I88 adapted to seat in the orifice I8 and to close communication between the chambers I8 and I6, and the extension I38 has a diametral passage I82 communicating with an axial passage I88 extended through the piston I I8 and the extensions I36 and I38. The open end of the passage I88 is adapted to receive the conical end I88 of the extension 88 on the head 86 to close the passage I88. A leak-proof cup I86 sleeved on the extension I36 is seated on the head I32, and another leak-proof cup I48 sleeved on the extension I38 is seated on the head I38. These cups prevent the passage of fluid to the rear of the piston heads, and a relatively heavy spring I58 interposed between the di'aphragmand the cup I88 urges the piston to itsseat on the conical head I 88 of the extension98 on the head 86, in which position the passage I48 is closed. I

In a normal operation of the brakes, when force-is applied to'the foot pedal lever 68 the shaft 66 to which the lever is secured is rocked,

. and this movement of the shaft is transmitted through the thrust rods 62 and 64, suitably connected to the shaft, to the pistons 58and 52' resulting. in moving these pistons on their compression strokes. As the pistons move on their compression strokes fluid is discharged from the cylinders I 8 and I2 past the..valves- I6 and 38 and through the conduits I8 and 28 into the fluid pressure motors '28, 26, 38 and 88, resulting in actuation of the motors with consequent movement of the friction elements 46 into engagement with the drums 88 against the resistance of the retractile springs 88.

Upon release of the foot pedal lever 68 a retractile spring, not shown, returnsthis lever to its normal position. As the foot pedal lever returns to its normal position the shaft. 66} is" As the pistons are urged to their retracted po-[ sitions, fluid is returned from. the fluid pressure motors 24, 26, 38 and 48 to the cylinders I8 and I2 due to the tension on the retractile springs 48 connected between the respective pairs of friction elements.

Under normal conditions of operation the 'pressure developed in the conduits I8 and 28 is sub stantially equal. Thus the pistons I88 and H8 move away from their respective seats immediately upon movement of the pistons 58 and 52 on their compression strokes. This movement of the pistons from their seats opens the passages I24 and I48 and establishes communication between the conduits I8 and 28, resulting in equalization ,of the pressure in the separate systems. This equalized pressure in the systems is maintained for a period of time 'during which the motors 28, 26, 88 and 48 are actuated to move the friction elements 86 into engagement with the drums 88. Upon attaining a predetermined pressure, the pistons I88,and II8 are moved sufiiciently to seat the conical ends I28 and IE8 of the extensions on the respective pistons I88 and H8 in the respective ends of the orifice I8 in the diaphragm I2.- This results in closing communication between the conduits I8 and 28 and segregating the systems for independent yet concomitant operation wherein the failure of one system would not in any way'efiect the other; and upon release of the pressure the pistons I88 and H8 are returned respectively under the influence of the respective springs I38 and I58 to their respective seats, wherein communication between the separate systems is again closed.

In an abnormal condition of operation, due to leakage or breakage of either of the'separate I from its seat or retracted position and not sufficient to cause movement of the piston M8 from its seat or retracted position, fluid would flow through the passages I28 and I22 in the piston I88 and the orifice I8 in the diaphragm E2 to the.

head I38 of the piston II8, and impose pressure on the head I38, which pressure when augmented by the tensile strength of the spring I58 would equal the pressure on the head II2 of the piston I88. Under this condition, as the pressure is built up in the respective systems, the differential in pressure remains, substantially constant, resulting in the retention of the piston III) on its seat or in'its retracted position wherein communication between the separate systems is closed, and thus the separate systems would operate individually.

Should the difi'erential in pressure in the separate systems be so small that both of the pistons I88 and H8 are caused to move from their rearate systems would be established with the resultant equalization of pressure in the systems.

However, should the pressure on the head II2 of the piston I 88 be greater than the pressure on the head I32 of the piston IIILthe piston III] would gradually move to its seat or retracted position because the pressure on the head I I2 of the piston I88 is transmitted to the head I380n the piston H8 and is augmented by the tensile strength of the spring I58. When the piston H8 is moved to its retracted position, communication between the systems is closed, and upon reaching a predetermined pressure on the head 2 of the piston I88, the conical end I22 of the extension onthe piston I88 seats in the orifice I8 in the diaphragm I2, completely sealing communication between the separate systems.

Although this invention has been described in connection with certain specificembodiments, the

principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

' Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is,

1. A fluid braking system comprising a pair of compressors, means for actuating the compressors in'unison, and interconnected corresponding fluid pressure valves connected respectively to the respective compressors and operable by fluid under pressure in the compressors to first establish communication between the compressors and secondly to intercept the communication between the compressors upon further increase in fluid pressure. i

2. A fluid braking system comprising a pair of compressors, a fluid pressure motor connected to each of the compressors, braking elements actuated by the motors, means for actuating the compressors in unison, oppositely disposed interconnected differential fluid pressure valves connected respectively to the respective compressors and operable upon initial pressure in the compressors to establish communication between the compressors, and at a predetermined higher pressure to intercept the communication between the compressors, and upon a difference of pressure in the compressors to segregate the compressor having the lower pressure.

3. A fluid braking system comprising a pair of compressors, a fluid pressure motor connected to each of the compressors, braking elements actuated by the fluid pressure motors, means for actuating the compressors in unison, oppositely disposed double diametral interconnected cylinders connected respectively to the respective compressors, a double-headed piston reciprocal in each of the cylinders having a passage therethrough, seats for said pistons, means urging the pistons to their seats, means for closing the passage in the pistons when the pistons are seated, and

other means carried by the pistons to close the connection between the cylinders upon attaining a predetermined pressure in the compressors.

4. A fluid pressure system comprising a pair of compressors, means operated by said compressors, a passageway connecting said compressors, normally closed valve means for inhibiting flow through said passageway until the fluid pressure created by said compressors reaches a predetermined value, normally open valve means for closing said passageway when the fluid pressure reaches a higher value than said predetermined value, and fluid pressure actuated means for opcrating said valve means.

pressure responsive means to open said lastnamed means upon the creation of a predetermined fluid pressure, and normally ineffective means in said passageway operable upon the creation of a fluid pressure higher than said predetermined pressure to close said passageway.

6. A fluid pressure system of the class described, comprising a pair of compressors, a fluid pressure motor connected to each compressor, a conduit connecting each motor with its compressor, a passageway connecting said conduits, a pair of fluid-operated pistons in said conduit, and a pair of alternately-operated, passageway-controlling valves controlled by each piston whereby said passageway is closed when either piston I is in either of its extreme positions.

7. In a hydraulic braking system of the class described the combination of a pair of compressors, a fluid pressure motor connected to each compressor, braking elements actuated by said motors, conduit means connecting said motors with said compressors, a passageway connecting said compressors, a pair of differential pistons in said passageway, a pair of valves associated with each piston whereby said passageway is closed when either piston is in either of its extreme positions, and means biasing each piston and normally maintaining one of its valves in closed position.

8. A fluid pressure system of the class described, comprising a pair of compressors, a mechanism connected to each compressor and operated in response to fluid pressure created thereby, a passageway connecting said compressors, valve means in said passageway cutting off communication therethrough until a predetermined fluid pressure is created by said compressors, means for opening said valve means upon the creation of said predetermined fluid pressure, and other valve means for closing communication through said passageway upon the creation of a second predetermined and higher pressure.

9. In a fluid pressure system of the class described, the combination of a pair of compressors, means actuated thereby, a passageway connecting said compressors, normally closed valve means in said passageway, mean for opening said valve means only upon the creation of a predetermined fluid pressure by both of said compressors, and means for closing said passageway upon the creation of a higher pressure by either of said I elements for each piston for cooperation with the valve elements formed by the ends of the pistons, and means for biasing said pistons.

HERBERT C. BOWEN. 

